There appears to be a need for an implantable glucose sensor which would have multiple potential uses not only in research but in therapeutic programs for diabetic patients, for example, as a part of a totally-implantable "glucose monitor system" or further in the future as the key component in a miniature, implantable, artificial, electrochemical beta cell. This program is focused upon the development of an electrochemical glucose sensor. Previous and current efforts have: 1) demonstrated that an electrochemical sensor utilizing a platinum glucose electrode is feasible; 2) embarked upon a program of basic electrochemical research to carefully characterize the mechanisms of glucose oxidation at a platinum electrode; 3) identified and partly characterized the mechanisms of both oxidation and inhibition effects of co-reactants such as urea and physiological amino acids; and 4) created a systematic methodologic approach to describe the activity of bare and membrane-covered platinum electrodes. Future work will be focused upon: 1) extension of the characteristics of glucose oxidation alone and on membrane-covered electrodes; 2) extension of the influence of individual co-reactants and simple co-reactant mixtures upon glucose oxidation on bare and membrane-covered electrodes; 3) measurement of glucose in serum ultra-filtrates; 4) evaluation of alternate electro-catalysts other than platinum; 5) development of a glucose sensor sub-assembly; 6) development of a total miniature glucose sensor and subsequently short-term and long-term in vitro testing of complete sensors.